The present invention relates to a hair treatment and, in particular, it concerns an apparatus to measure a hair reflectance spectrum and a method to determine an appropriate hair treatment based directly upon a hair reflectance spectrum.
By way of introduction, each strand of hair consists of three layers, namely, the medulla, cortex and cuticle. The medulla is the innermost layer of the hair and is composed of a softer keratin-rich material and its occurrence in human hair appears to be variable, usually being present in large thick hairs. The cuticle is the outermost surface of the hair shaft and is composed of a very hard keratinous substance. It consists of flattened platelets of amorphous keratin, wrapped around the hair shaft in several layers, each layer overlapping the adjacent one, progressing from the root to the tip of the hair. Lastly, the cortex is the inner bulk of the hair, which forms the main body of the hair. The cortex is disposed between the medulla and the cuticle. It is composed of a much softer, fibrous, crystalline keratin. It provides strength, color and texture to the hair. Human hair gets its colors from specialized cells in the hair follicle called melanocytes that produce the pigment for hair. Humans normally produce two type of melanin, namely, Eumelanin and Pheomelanin. Eumelanin is associated with a dark brown color and Pheomelanin is associated with an orange color. Brown and black hair is given its color primarily by Eumelanin. Red hair is given its color primarily by Pheomelanin. Blond hair and hair that has gone white with age have very few of either pigment.
A hair treatment to change an initial hair color to a final hair color normally involves bleaching and/or dyeing. The hair may need to be bleached to reduce the natural Eumelanin and Pheomelanin pigments. The extent of the bleaching depends upon the initial and final hair color. A diluted solution of hydrogen peroxide is generally used as the bleaching agent. The oxygen in the diluted solution of hydrogen peroxide opens up the cuticle of the hair so that the bleaching agent can enter into the cortex to remove the Eumelanin and Pheomelanin pigments. Once bleaching is complete, the hair dye is applied to the hair, if necessary. The hair dye also includes oxygen, which opens up the cuticle of the hair so that the coloring agent can enter into the cortex.
Therefore, the accuracy of the hair coloring process relies upon the skill of the hairdresser to determine how much bleaching is required and which hair dye or combination of hair dyes should be applied to provide the customer with the desired final color. Part of the hairdresser's skill is based upon accumulated experience as well as guidelines issued by the dye manufacturer. However, the final color is often a matter of surprise to both the hairdresser and the customer.
Of relevance to the present invention is U.S. Pat. No. 4,434,467 to Scott. The patent to Scott describes a method whereby the customer chooses a color from a database that is the closest match to his or her own hair color. The customer then chooses a desired final color from the database. The computer then suggests a treatment based on the manufacturer instructions. A shortcoming of the aforementioned system is that the customer has to determine by visual comparison, the closest match to his or her own hair color. A further shortcoming of the aforementioned system is that the system is limited to hair treatments, which are based upon a fixed selection of initial hair colors, thereby not taking into account the individual's hair color.
Also of relevance to the present invention is U.S. Pat. No. 5,609,484 to Hawiuk. Hawuik teaches the use of color filament swatches to recreate the initial hair color and then to add color filament swatches, which are related to a known hair dye, to see how the initial hair color is affected by the hair dye. A shortcoming of the aforementioned system is that the system is not accurate. A further shortcoming of the aforementioned system is that determining the initial color involves a high degree of estimation. An additional shortcoming of the aforementioned system is that this system does not address bleaching of the initial hair color.
Of most relevance to the present invention is U.S. Pat. Nos. 6,067,504, 6,157,445, 6,308,088, 6,314,372 and 6,330,341 to MacFarlane, et el. These patents discuss a method, which first includes obtaining a reflectance spectrum from a sample of hair. The coefficients of the Hunter L, a and b color coordinates of the reflectance spectrum of the hair sample are then analyzed by a computer. The initial hair color is then classified by the computer according to a range of coefficients of the color coordinates stored in a lookup table. A user then chooses a desired hair color from a choice of possible final colors. The computer then determines the appropriate hair treatment based upon a hair treatment stored in a lookup table for the initial hair color and the desired final hair color. A shortcoming of the aforementioned system is due to the initial hair color being classified according to an artificial color, which fits into a range of possible colors. Therefore, the suggested hair treatment does not accurately reflect the users initial hair color. A further shortcoming of the aforementioned system is that the creation and maintenance of the hair treatment lookup table requires a vast number of experiments. For example, for each hair dye, experiments are needed for all the possible initial and final hair colors that can be achieved for that dye. Additionally, the use of the L, a, b color coordinate system can be misleading in certain cases. For example, two samples of hair, which look substantially the same to the human eye may have the same L, a, b color coordinate values even though they have different spectrums of reflectance. For example, one natural blond hair sample which is colored with dye A, may have the same color coordinates as another hair sample, say, a brown hair colored with a dye B. Therefore, simply looking at the L, a, b color coordinates may lead to spurious results.
There is therefore a need for a method to determine a hair treatment based directly upon a person's initial hair color.
Additionally, a large sample of hair is typically required to produce a usable reflectance spectrum of hair. Therefore, there is a need for a system and method to produce a usable reflectance spectrum of hair without having to remove the hair from the customer's head.